Vehicle seat having a backrest

ABSTRACT

The invention relates to a vehicle seat having a backrest which comprises a backrest part and a backrest base element, the backrest part comprising a middle backrest element which is arranged pivotably on the backrest base element, wherein the backrest part comprises two lower backrest side elements and two upper backrest side elements, which are each mechanically coupled to the middle backrest element, wherein the two lower backrest side elements are arranged pivotably on the backrest base element, wherein at least one joint device is provided in each case between a lower backrest side element and an upper backrest side element, wherein a lower backrest side element and an upper backrest side element are each arranged at an angle αL, αR to one another, wherein pivoting of the middle backrest element causes a change in the angle αL, αR.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of German Patent Application No. 102020134186.5 filed Dec. 18, 2020, the contents of which are incorporated herein by reference in its entirety.

FIELD

The invention relates to a vehicle seat having a backrest which comprises a backrest base element and a backrest part, the backrest part comprising a middle backrest element which is arranged pivotably on a backrest base element.

BACKGROUND

When commercial vehicles, such as tractors, forklift trucks, etc., are used it is often necessary for the driver to look to the rear or to the side, as reversing is necessary or components attached or coupled to the rear or side of the vehicle must be monitored or checked. If necessary, actuators arranged at the side or at the rear can also be operated. The driver or occupant must turn his upper body accordingly. In this turning movement, however, conventional vehicle seats do not provide the occupant with appropriate support. Due to the lack of support, the driver tires more quickly and the seating comfort is considerably reduced.

SUMMARY

The object of the present invention is to provide a vehicle seat which solves the aforementioned problems.

The object is achieved by the subject matter of independent claim 1. Advantageous embodiments can be found in the dependent claims.

The core concept of the invention is a vehicle seat having a backrest which comprises a backrest part and a backrest base element, the backrest part comprising a middle backrest element which is arranged pivotably on the backrest base element, wherein the backrest part comprises two lower backrest side elements and two upper backrest side elements, which are each mechanically coupled to the middle backrest element, wherein the two lower backrest side elements are arranged pivotably on the backrest base element, wherein at least one joint device is provided between a lower backrest side element and an upper backrest side element, wherein a lower backrest side element and an upper backrest side element are each arranged at an angle (α_(L), α_(R)) to one another, wherein pivoting of the middle backrest element causes a change in the angle (α_(L), α_(R)).

Accordingly, the vehicle seat according to the invention comprises an at least five-part backrest part which serves to support the occupant. The middle backrest element, the two lower backrest side elements and the two upper backrest side elements are also referred to below as the backrest elements. The mechanical couplings and the articulation of an upper backrest side element on an associated lower backrest side element bring about an ergonomically optimal adaptation of the backrest part to a turning movement of an occupant. Furthermore, such a pivotable backrest part can also serve to isolate transverse accelerations (swaying).

The backrest extends along a height axis Z, a width axis Y and a longitudinal axis X. The vehicle seat extends along a height axis Z′, a width axis Y′ and a longitudinal axis X′.

A lower backrest side element and an upper backrest side element are preferably arranged on the left side of the middle backrest element and form a left side portion of the backrest part. A further lower backrest side element and a further upper backrest side element are advantageously arranged on the right side of the middle backrest element and form a right side portion of the backrest part.

In a initial position of the backrest or the vehicle seat, the middle backrest element is preferably arranged substantially in a first plane E1, which is spanned by a height axis Z of the backrest and a width axis Y of the backrest. Advantageously, in the initial position of the backrest, the left side portion of the backrest part is arranged substantially in a second side plane E2, which is spanned by the height axis Z of the backrest and a first axis A1. In the initial position of the backrest, the right side portion of the backrest part is advantageously arranged substantially in a third side plane E3, which is spanned by the height axis Z of the backrest and a second axis A2. The width axis Y and the first axis A1 preferably enclose an angle of inclination β₁. The width axis Y and the second axis A2 preferably enclose an angle of inclination β₂. The angles of inclination β₁, β₂ are preferably in a range between 5° and 80°, more preferably in a range between 20° and 70°, more preferably in a range between 30° and 50°. The first angle of inclination β₁ is advantageously equal to the second angle of inclination β₂. This forwardly inclined arrangement of the side portions provides support for the occupant in the lateral directions. The backrest thus advantageously has a type of shell shape which gives the occupant a certain amount of support with respect to forces acting in the width direction.

The upper backrest side elements are preferably arranged along the height axis above the lower backrest side elements. According to a preferred embodiment, at least in the initial position of the backrest, the upper backrest side elements and the lower backrest side elements are spaced apart from one another. Advantageously, at least in the initial position of the backrest, a slot is formed between the upper backrest side elements and the lower backrest side elements. Advantageously, starting from an inner region of a side portion of the backrest part, the slot runs obliquely upwards along the height axis to an outer region of a side portion of the backrest part. The inner region of the side portion is arranged closer to the middle backrest element along the width direction Y than the outer region of the side portion. The two slots have the advantage of, on the one hand, allowing ventilation of the occupant's back, and on the other hand, facilitating an advantageous relative movement of the upper and lower backrest side elements with respect to one another.

A first coupling mechanism is preferably provided, by means of which the middle backrest element is mechanically coupled to the two lower backrest side elements. A second coupling mechanism is advantageously provided, by means of which the middle backrest element is mechanically coupled to the two upper backrest side elements. In a preferred initial position of the vehicle seat or the backrest, the occupant is facing forwards. In this advantageous initial position, the middle backrest element extends substantially along the height axis Z and thus serves as a support for the spinal column region or a part of the spinal column region of the occupant. Advantageously, a turning movement of an occupant results in an introduction of force into the backrest part. This introduction of force acts, depending on the seated posture of the occupant, on one, several or all of the at least five backrest elements. Advantageously, due to the advantageous mechanical coupling of the upper and lower backrest side elements to the middle backrest element, the introduction of force acts on all the backrest elements. The introduction of force preferably causes the middle backrest element and the two lower backrest side elements to pivot relative to the backrest base element. The middle backrest element is preferably pivoted in directions parallel to the width axis Y. The first coupling mechanism and the second coupling mechanism advantageously form a forced control.

According to a further advantageous embodiment, a joint device is provided in each of the outer regions of the left side portion and the right side portion of the backrest part. The at least one joint device is advantageously arranged at least in portions in the associated slot. In the initial position of the backrest, a distance between a lower backrest side element and a correspondingly associated upper backrest side element in the slot is preferably substantially constant along its entire length. Advantageously, when the middle backrest element is pivoted along a direction parallel to the width axis, a distance between a lower backrest side element and an upper backrest side element changes at least in the inner region of a side portion of the backrest part due to the mechanical couplings and a deflection of the joint device. Preferably, the distance between a lower backrest side element and a correspondingly associated upper backrest side element becomes smaller when pivoting in the direction of the associated side portion.

According to a further advantageous embodiment, the respective joint device comprises a swivel joint and a ball joint. A connecting rod element is preferably arranged rotatably on the lower backrest side element through the swivel joint. A ball socket of the ball joint, in which a ball head of the ball joint is received, is advantageously arranged on the connecting rod element, wherein the ball head is connected to the upper backrest side element by means of a ball stud. The ball joint has three degrees of freedom that allow movements in all three planes of space. A movement of the ball joint in all degrees of freedom and a rotational movement of the swivel joint preferably take place when the middle backrest element is pivoted or due to an introduction of force by a turning movement of the occupant.

According to a further advantageous embodiment, the second coupling mechanism comprises guide devices, by means of which in each case an upper backrest side element is arranged on the middle backrest element. Accordingly, the left upper backrest side element is preferably arranged with a left guide device on a left side region of the middle backrest element. Accordingly, the right upper backrest side element is preferably arranged with a right guide device on a right side region of the middle backrest element. The guide device advantageously allows a translational movement of the upper backrest side element relative to the middle backrest element along a longitudinal axis LA of the middle backrest element. The guide device preferably allows a rotary movement of the upper backrest side element relative to the middle backrest element about an axis of rotation DA which runs parallel to the longitudinal axis LA of the middle backrest element. When the middle backrest element is pivoted, there is advantageously both a translational movement of the upper backrest side element relative to the middle backrest element and a rotary movement of the upper backrest side element relative to the middle backrest element.

According to a preferred embodiment, the guide device comprises a sliding rod which is attached to the middle backrest element. At least one, preferably two, sliding elements can slide on this sliding rod. The sliding movement is, on the one hand, a translational movement along the longitudinal direction of the sliding rod, which runs parallel to the longitudinal axis LA of the middle backrest element, and a rotary movement around the sliding rod. Of course, other types of guide systems which allow a translational movement and a rotary movement would also be conceivable. These would be, for example, interlocking guide rods etc.

According to a further advantageous embodiment, the backrest base element has a middle region which extends substantially parallel to the first plane E1. It is also advantageous that the backrest base element has two side regions, which are advantageously rigidly connected to the middle region. The backrest base element is preferably designed integrally or in one piece. A left side region of the backrest base element preferably extends substantially parallel to the second side plane E2. A right side region of the backrest base element preferably extends substantially parallel to the third side plane E3. Such an angled design of the backrest base element preferably predetermines the design of the backrest part in the initial position of the backrest.

According to a further advantageous embodiment, the middle backrest element is arranged on the middle region of the backrest base element so as to be pivotable about a first pivot axis. The first pivot axis can advantageously be a real or an imaginary pivot axis which extends parallel to the longitudinal axis X of the backrest. The middle backrest element is preferably mounted on the backrest base element by means of a first pivot axis SA1. A first fastening element is preferably provided, which is firmly connected to the middle backrest element and which is pivotable about the first pivot axis SA1. By the use of a stable fastening element, the lower backrest side element can be constructed more easily.

According to a particularly preferred embodiment, the lower backrest side elements are each arranged on the side regions of the backrest base element so as to be pivotable about a second or third pivot axis. The second pivot axis and/or the third pivot axis can advantageously be a real or an imaginary pivot axis. The second and third pivot axes SA2, SA3 preferably extend obliquely upwards along the longitudinal axis X and the height axis Z. The second and/or the third pivot axis extend obliquely upwards, starting from a rear region of the backrest, which faces away from the occupant, to the respective lower backrest side elements or the respective fastening elements. The second and/or the third pivot axis SA2, SA3 thus preferably enclose an angle γ₂, γ₃ with a plane which is spanned by the longitudinal axis X and the width axis Y. These angles γ₂, γ₃ are preferably in a range between 10° and 80°, more preferably in a range between 20° and 70°, more preferably in a range between 30° and 60°. A second fastening element is preferably provided which is firmly connected to the lower backrest side element arranged on the left and which is pivotable about the second pivot axis. A third fastening element is preferably provided which is firmly connected to the backrest side element arranged on the right and which is pivotable about the third pivot axis. Due to the course of the second and third pivot axis obliquely upwards and forwards, when the lower backrest side elements are pivoted, the advantageous effect occurs that an upper edge region along the height axis Z and simultaneously an outer edge region of the lower backrest side elements along the width axis Y moves forwards or backwards along the longitudinal axis. Thus, when this region pivots to a certain side, it moves forwards and when it pivots in the opposite direction it moves backwards.

According to a further preferred embodiment, the first coupling mechanism transmits a pivoting movement of the middle backrest element to the left lower backrest side element and/or to the right lower backrest side element and vice versa. The first coupling mechanism preferably transmits a pivoting movement of the first fastening element to the second fastening element and to the third fastening element. The first coupling mechanism preferably transmits a pivoting movement of the second fastening element and/or of the third fastening element to the first fastening element. The first coupling mechanism advantageously has a first coupling rod which connects the first fastening element and the second fastening element. The first coupling mechanism preferably has a second coupling rod which connects the first fastening element and the third fastening element. The coupling rods are preferably each fastened to the fastening elements by means of a ball joint. However, the invention is not limited to this embodiment. Of course, other couplings which can transmit the pivoting movements correspondingly can also be considered. Such coupling mechanisms could be, for example, gears, Bowden cables or the like.

According to a further preferred embodiment, the upper backrest side elements and the lower backrest side elements are designed as plate-like elements. The plate-like elements are advantageously designed to accommodate upholstery elements. However, it would also be conceivable that no further upholstery elements are provided or that only one upholstery layer is applied to the plate-like elements. The advantageous upholstery elements and/or the plate-like elements form a corresponding bearing or support surface for the occupant. This bearing surface is preferably at least divided into two by the slot.

When the middle backrest element is pivoted towards a side portion of the backrest part, the angle (α_(L), α_(R)) is advantageously an obtuse angle. When the middle backrest element is pivoted towards a side portion of the backrest part, an upper edge region of the lower backrest side element and a lower edge region of the upper backrest side element are preferably displaced forwards at least in an outer edge region of the side portion along the longitudinal axis X. This region which is moved forwards is perceived as a kind of bulge towards the front of the bearing surface. When the upper body turns while sitting, the side rear region of the upper body bends a little. This region is supported by the described bulge of the bearing surface, which provides an ergonomically comfortable vehicle seat.

According to a further preferred embodiment, the middle backrest element is designed in two parts. The two portions of the middle backrest element are preferably connected to one another by a further joint device. The joint device is preferably arranged in a lower region of the middle backrest element. The further joint device is advantageously arranged in or above the occupant's lumbar region. An upper portion of the middle backrest element is advantageously pivotable relative to the lower portion along the longitudinal axis X. A posture adjustment or lordosis/kyphosis of the occupant can be compensated for by such pivoting. Advantageously, the inclination of the upper portion of the middle backrest element can be adjusted hydraulically, pneumatically or also manually by an actuating drive, for example an electric motor.

According to a further preferred embodiment, the backrest base element is arranged on a seat base element so as to be rotatable about an axis of inclination. In this way the inclination of the backrest can be modified. This inclination can of course be adjusted by a motor, mechanically or in some other way. Furthermore, a locking device can be provided, by means of which this inclination can be locked.

According to a further preferred embodiment, a locking device is provided, by means of which the rotational position of the backrest part can be locked. A rotational position is defined by the pivoting of a middle backrest element, the pivoting of the lower backrest side elements and the relative changes in the orientations or the positions of the backrest elements with respect to one another. The initial position of the backrest is of course also to be understood as such a rotational position. The locking device can be designed, for example, in such a way that the pivoting of the middle backrest element is locked. Due to the mechanical coupling of the backrest elements, the further backrest elements are also fixed in their position or orientation by such a locking mechanism. The locking device can be operated via an operating device. The operating device can comprise a mechanical system, for example a Bowden cable system, or an electrical system, for example an electric actuating drive.

A resetting device is advantageously provided, by means of which the backrest part can be returned to the initial position. The resetting device can be a mechanical device, for example a spring arrangement, an electric actuating drive or a hydraulic or pneumatic device.

According to a further preferred embodiment, a drive unit is provided by means of which the backrest part can be brought into a rotational position. The drive unit can be designed, for example, in such a way that the pivoting of the middle backrest element is driven. As a result of the mechanical coupling of the backrest elements, such a drive also brings the further backrest elements into a corresponding position or orientation. Such a drive unit can be, for example, an actuating drive, preferably with an electric motor, or a hydraulic or pneumatic drive.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages, aims and characteristics of the present invention are explained with reference to the following description of the attached drawings. Similar components may have the same reference signs in the various embodiments.

In the drawings:

FIG. 1a, 1b, 1c are isometric views of the vehicle seat according to an embodiment in a initial position of a pivoting to the left and a pivoting to the right;

FIG. 2a, 2b, 2c are isometric views of a vehicle seat according to an embodiment without upholstery elements in a initial position of a pivoting to the left and a pivoting to the right;

FIG. 3a, 3b, 3c are top views of a vehicle seat according to an embodiment in a initial position of a pivoting to the left and a pivoting to the right;

FIG. 4a, 4b, 4c are top views of a vehicle seat according to an embodiment without upholstery elements in a initial position of a pivoting to the left and a pivoting to the right;

FIG. 5a, 5b, 5c are isometric views of a vehicle seat according to an embodiment in a initial position of a pivoting to the left and a pivoting to the right;

FIG. 6a, 6b, 6c are isometric views of a vehicle seat according to an embodiment in a initial position of a pivoting to the left and a pivoting to the right;

FIG. 7a, 7b, 7c are views from behind of a vehicle seat according to an embodiment in a initial position of a pivoting to the left and a pivoting to the right;

FIG. 8 is an isometric view of a backrest according to an embodiment;

FIG. 9a, 9b are a rear view and a front view of a backrest base member;

FIG. 10a to 10f are different views and sectional views of a backrest base element according to an embodiment;

FIG. 11 is a front view and a rear view of a backrest part according to an embodiment;

FIG. 12 is an exploded view of a backrest part according to an embodiment;

FIG. 13a, 13b, 13c are views of a backrest part according to an embodiment in a initial position of a pivoting to the left and a pivoting to the right.

DETAILED DESCRIPTION

FIG. 1 to 13 c show a vehicle seat 1 having a backrest 2 which comprises a backrest part 3 and a backrest base element 4, the backrest part 3 comprising a middle backrest element 5 which is arranged pivotably on the backrest base element 4, wherein the backrest part 3 comprises two lower backrest side elements 6 a, 6 b and two upper backrest side elements 7 a, 7 b, which are each mechanically coupled to the middle backrest element 5, wherein the two lower backrest side elements 6 a, 6 b are arranged pivotably on the backrest base element 4, wherein at least one joint device 8 a, 8 b is provided in each case between a lower backrest side element 6 a, 6 b and an upper backrest side element 7 a, 7 b, wherein a lower backrest side element 6 a, 6 b and an upper backrest side element 7 a, 7 b are arranged at an angle α_(L), α_(R) to one another, wherein pivoting of the middle backrest element 5 causes a change in the angle α_(L), α_(R). Thus, at least one joint device 8 a, 8 b is provided in each case between a lower backrest side element 6 a, 6 b and an upper backrest side element 7 a, 7 b, wherein the upper backrest side elements 7 a, 7 b and the lower backrest side elements 6 a, 6 b are pivotable relative to one another, and the upper backrest side elements 7 a, 7 b and the lower backrest side elements 6 a, 6 b can each be arranged at an angle α_(L), α_(R) to one another.

The backrest 2 extends along a height axis Z, a width axis Y and a longitudinal axis X. The vehicle seat 1 extends along a height axis Z′, a width axis r and a longitudinal axis X′.

The vehicle seat 1 can thus assume various rotational positions 10 a, 10 b, 10 c. In these rotational positions 10 a, 10 b, 10 c, the backrest elements 5, 6 a, 6 b, 7 a, 7 b assume certain positions relative to one another. A first rotational position is the initial position 10 c of the vehicle seat 1. In FIG. 1a , 2 a, 3 a, 4 a, 5 a, 6 a, 7 a, the vehicle seat 1 is shown in the initial position 10 c. In the initial position 10 c of the vehicle seat 1 or the backrest 2, the occupant is facing forwards and the middle backrest element 5 extends substantially along the height axis Z and thus serves as a support for the spinal column region or a part of the spinal column region of the occupant. In FIG. 13a , the backrest part 3 or the backrest elements 5, 6 a, 6 b, 7 a, 7 b are shown in the initial position 10 c. If the driver turns to the right (viewing direction to the right), the backrest elements 5, 6 a, 6 b, 7 a, 7 b or the backrest part 3 pivot to the left and assume a second rotational position 10 a. In FIG. 1b, 2b, 3b, 4b, 5b, 6b, 7b , the vehicle seat 1 is shown in this rotational position 10 a. The backrest elements 5, 6 a, 6 b, 7 a, 7 b or the backrest part 3 are pivoted 20° to the left. In FIG. 13b , the backrest part 3 or the backrest elements 5, 6 a, 6 b, 7 a, 7 b are shown in this rotational position 10 a. If the driver turns to the left (viewing direction to the left), the backrest elements 5, 6 a, 6 b, 7 a, 7 b or the backrest part 3 pivot to the right and assume a third rotational position 10 c. In FIG. 1c , 2 c, 3 c, 4 c, 5 c, 6 c, 7 c, the vehicle seat 1 is shown in this rotational position 10 b. The backrest elements 5, 6 a, 6 b, 7 a, 7 b or the backrest part 3 are pivoted 20° to the right. In FIG. 13c , the backrest part 3 or the backrest elements 5, 6 a, 6 b, 7 a, 7 b are shown in this rotational position 10 b. It should be pointed out that the rotational positions 10 a, 10 b are exemplary positions; the rotation or pivoting of the backrest part 5 can take place continuously into further rotational positions.

The vehicle seat 1 comprises a seat base element 32, which is designed in the form of a plate and can be arranged on a further seat substructure or on a vehicle. A seat part 35, which comprises one or more upholstery elements, can be arranged on the seat base element 32. The seat part 35 can be arranged displaceably along the longitudinal axis X′ relative to the seat base element 32. A locking device and/or a drive unit can be provided which locks and/or drives this displacement. The seat base element 32 comprises support elements 36 arranged on the outside along the width axis Y′. The support elements 36 are arranged at the rear along the longitudinal axis X′. The backrest base element 4 is arranged on these support elements 36 so as to be pivotable about an axis of inclination NA. Here, too, a locking device and/or a drive unit can be provided which locks and/or drives this inclination of the backrest 2 or the backrest part 3.

The backrest part 3 comprises a lower backrest side element 6 a and an upper backrest side element 7 a, which are arranged on the left side of the middle backrest element 5 and thus form a left side portion 9 a of the backrest part 3. The backrest part 3 further comprises a lower backrest side element 6 b and an upper backrest side element 7 b, which are arranged on the right side of the middle backrest element 3 and form a right side portion 9 b of the backrest part 3. The upper backrest side elements 7 a, 7 b and the lower backrest side elements 6 a, 6 b are designed as plate-like elements which are designed to accommodate upholstery elements 29. For this purpose, the plate-like elements have a border which extends forwards. FIG. 1a, 1b, 1c , 3 a, 3 b, 3 c, 5 a, 5 b, 5 c, 6 a, 6 b, 6 c, 7 a, 7 b, 7 c show the vehicle seat 1 or the backrest 2 with such upholstery elements 29. FIG. 2a, 2b, 2c, 4a, 4b, 4c , 8, 11, 12, 13 a, 13 b, 13 c show the vehicle seat 1 or the backrest 2 without upholstery elements 29. The seat part 35 is also not shown in these drawings. The upholstery elements 29 form a two-part bearing/support surface for the occupant.

In the initial position 10 c of the backrest 2, the middle backrest element 5 is arranged substantially in a first plane E1, which is spanned by a height axis Z of the backrest 2 and a width axis Y of the backrest 2. The left side portion 9 a of the backrest part 3 is arranged in the initial position 10 c substantially in a second side plane E2, which is spanned by the height axis Z of the backrest 2 and a first axis A1. Furthermore, the right side portion 10 b of the backrest part 2 is arranged substantially in a third side plane E3 which is spanned by the height axis Z of the backrest and a second axis A2. The width axis Y and the first axis A1 enclose a first angle of inclination β₁ and the second axis A2 encloses an angle of inclination β₂ with the width axis Y. This is shown in FIGS. 1 and 8. The angles of inclination β₁, β₂ are preferably in a range between 5° and 80°, more preferably in a range between 20° and 70°, more preferably in a range between 30° and 50°. The occupant is supported laterally by the side portions 9 a, 9 b which are oriented obliquely forwards. This is particularly advantageous if the vehicle sways.

The backrest base element 4 is explicitly shown in FIG. 8, 9 a, 9 b, 10 a to 10 f. It can be seen here that the backrest base element 4 has a middle region 4 c which extends substantially parallel to the first plane E1. Furthermore, the backrest base element 4 has two side regions 4 a, 4 b. A left side region 4 a of the backrest base element 4 extends substantially parallel to the second side plane E2 and a right side region 4 b of the backrest base element 4 extends substantially parallel to the third side plane E3. The lower backrest side elements 6 a, 6 b are each arranged on the side regions 4 a, 4 b of the backrest base element 4 so as to be pivotable about a second pivot axis SA2 or a third pivot axis SA3. The middle backrest element 5 is arranged on the middle region 4 c of the backrest base element 4 so as to be pivotable about a first pivot axis SA1. A fastening element 25, 26, 23 is pivotably arranged in each of the mentioned regions 4 a, 4 b, 4 c. The middle backrest element and the lower backrest side elements 6 a, 6 b are fastened to these fastening elements 25, 26, 23. One fastening element 23 is arranged in the middle region 4 c so as to be pivotable about a pivot axis SA1. The second fastening element 24 is firmly connected to the lower backrest side element 6 a arranged on the left side and is pivotable about the second pivot axis SA2 relative to the backrest base element 4. The third fastening element 25 is firmly connected to the lower backrest side element 6 b arranged on the right side and is pivotable about the third pivot axis SA3 relative to the backrest base element 4.

The pivot axis SA1 is substantially horizontal, i.e. it extends in a plane which is spanned by the width axis Y and the longitudinal axis X and/or is parallel to the longitudinal axis X. In contrast to this, the pivot axes SA2 and SA3 are not oriented horizontally, but inclined. The second pivot axis SA2 and the third pivot axis SA3 extend obliquely upwards along the longitudinal axis X and the height axis Z. The second pivot axis SA2 and the third pivot axis SA3 accordingly run obliquely upwards, starting from a rear region of the backrest 2, which faces away from the occupants, to or through the respective lower backrest side elements 6 a, 6 b or the respective fastening elements 24, 25. The second and the third pivot axis SA2, SA3 thus preferably enclose an angle γ₂, γ₃ with a plane which is spanned by the longitudinal axis X and the width axis Y. These angles γ₂, γ₃ are preferably in a range between 10° and 80°, more preferably in a range between 20° and 70°, more preferably in a range between 30° and 60°. Due to the inclined pivot axes SA2 and SA3, when the lower backrest side elements 6 a, 6 b are pivoted, an upper edge region 30 a, 30 b of the lower backrest side element 6 a, 6 b is displaced forwards towards the occupant.

A first coupling mechanism 14 is provided, by means of which a mechanical coupling of the middle backrest element 5 to the two lower backrest side elements 6 a, 6 b takes place. Accordingly, the first coupling mechanism is a forced control, which has the effect that a pivoting movement of the middle backrest element 5 is transmitted to the lower backrest side elements 6 a, 6 b. Likewise, a pivoting movement of a lower backrest side element 6 a, 6 b is transmitted to the middle backrest element 5 and the further lower backrest side element 6 a, 6 b. A turning movement of an occupant results in a force being introduced into the backrest part 3. The introduction of force in turn causes the middle backrest element 5 and the two lower backrest side elements 6 a, 6 b to pivot relative to the backrest base element 4.

The first coupling mechanism comprises a first coupling rod 26 which connects the first fastening element 23 and the second fastening element 24. Furthermore, the first coupling mechanism comprises a second coupling rod 27, which connects the first fastening element 23 and the third fastening element 25. The coupling rods are each fastened to the respective fastening elements 23, 24, 25 by means of a ball joint 28. Due to the inclined arrangement of the lower backrest side elements 6 a, 6 b relative to the middle backrest element 5 or the inclined arrangement of the second fastening element 24 and the third fastening element 25 relative to the first fastening element 23, the coupling rods are angled in such a way that a first portion of the coupling rod runs substantially parallel to the first portion of the backrest base element 4 and a second portion runs substantially parallel to the second portion of the backrest base element 4. The joint socket of the ball joints is arranged at the respective end of the coupling rods 26, 27. The respective ball head is fastened to the fastening elements 23, 24, 25 via a ball stud.

Accordingly, two ball joints 28 are arranged on the first fastening element. In the initial position 10 c, these two ball joints are located on an axis substantially parallel to the width axis X. When the backrest elements 5, 6 a, 6 b, 7 a, 7 b are pivoted, a ball joint 28 is displaced downwards along the height axis and a ball joint is displaced upwards along the height axis Z. The ball head then rotates according to this movement. For example, in the case of pivoting to the left, the left ball joint 28, which is connected to the first coupling rod 26, is displaced downwards. The right ball joint 28, which is connected to the second coupling rod 27, is displaced upwards. This is shown in FIG. 7a, 7b, 7c . The ball joints 28, which are arranged on the second fastening element 24 and the third fastening element 25, transmit a pushing or pulling movement. Due to the inclined arrangement of the lower backrest side elements 6 a, 6 b relative to the middle backrest element 5 or the inclined arrangement of the second fastening element 24 and the third fastening element 25, the respective ball head rotates forwards or backwards on the second fastening element 24 and the third fastening element 25.

Furthermore, a second coupling mechanism 15 is provided, by means of which the middle backrest element 5 is mechanically coupled to the two upper backrest side elements 7 a, 7 b. The second coupling mechanism 15 comprises a left guide device 22 a and a right guide device 22 b, by means of which the left upper backrest side element 7 a and the right backrest side element 7 b, respectively, are arranged on the middle backrest element 5. The respective guide device 22 a, 22 b allows a guided translational movement of the upper backrest side elements 7 a, 7 b relative to the middle backrest element 5 along a longitudinal axis LA of the middle backrest element. Furthermore, the guide devices 22 a, 22 b allow a rotary movement of the upper backrest side elements 7 a, 7 b relative to the middle backrest element 5 about an axis of rotation DA which runs parallel to the longitudinal axis LA of the middle backrest element 5.

According to a preferred embodiment, the guide device comprises a sliding rod 41 which is fastened to the middle backrest element. In the present case, at least two, preferably three, holding elements 42 are provided for this purpose. At least one, preferably two, sliding elements 43, which are arranged on the corresponding upper backrest side element 7 a, 7 b, can slide on this sliding rod. The sliding movement is, on the one hand, a translational movement along the longitudinal direction of the sliding rod 41, which runs parallel to the longitudinal axis LA of the middle backrest element, and a rotary movement around the sliding rod. The sliding rod 41 preferably has a circular cross section. The sliding elements 42 comprise a bore through which the sliding rod 42 is guided. The sliding movement of the sliding elements 42 is, on the one hand, a translational movement along the longitudinal direction of the sliding rod 41, which runs parallel to the longitudinal axis LA of the middle backrest element 5, and a rotary movement around the sliding rod 42 or about an axis of rotation DA, which is a central axis of the respective sliding rod 42. The holding elements 42 can serve as a stop with regard to the translational movement of the sliding elements 43. This can be clearly seen in FIG. 7a, 7b, 7c , 11, 12, 13 a, 13 b, 13 c.

In the case of an exemplary displacement to the left into the second rotational position 10 a, the left upper backrest side element 7 a is accordingly displaced upwards along the longitudinal axis LA of the middle backrest element 5. The left upper backrest side element 7 a accordingly protrudes beyond the end of the longitudinal extent of the middle backrest element 5. At the same time, the left upper backrest side element 7 a rotates about the axis of rotation DA, so that it is rotated forwards towards the occupant. The right upper backrest side element 7 b is displaced downwards along the longitudinal axis LA of the middle backrest element 5. The right upper backrest side element 7 b accordingly dips below the end of the longitudinal extension of the middle backrest element 5. At the same time, the right upper backrest side element 7 b rotates about the axis of rotation DA, so that it is rotated forwards towards the occupant. Such an exemplary second rotational position 10 a is shown in FIG. 1b, 2b, 3b, 4b, 5b, 6b, 7b, 13b . A displacement to the right can be described analogously and is shown in FIG. 1 c, 2 c, 3 c, 4 c, 5 c, 6 c, 7 c, 13 c.

The upper backrest side elements 7 a, 7 b and the lower backrest side elements 6 a, 6 b are spaced apart from one another along the height axis Z such that a slot 11 a, 11 b is formed between these two elements 6 a, 6 b, 7 a, 7 b. Starting from an inner region 12 a, 12 b of a side portion 9 a, 9 b, this slot 11 a, 11 b runs obliquely upwards along the height axis Z to an outer region 13 a, 13 b of a side portion 9 a, 9 b of the backrest part 3. The two slots 11 a, 11 b thus run in a V-shape towards the middle backrest element 5. The slot 11 a, 11 b encloses an angle δ with a horizontal axis 39. The horizontal axis 39 lies in a plane which is spanned by the width axis Y and the longitudinal axis X. The angle δ is preferably in a range between 20° and 70°, preferably in a range between 30° and 60°, more preferably in a range between 40° and 50°. This is shown, for example, in FIGS. 8 and 13 a. The upper backrest side elements 7 a, 7 b and the lower backrest side elements 6 a, 6 b have a corresponding shape. An upper region 37 a, 37 b of the lower backrest side elements 6 a, 6 b has substantially the shape of an irregular right-angled triangle. The hypotenuse of this triangle forms the upper edge of the lower backrest side elements 6 a, 6 b facing the slot 11 a, 11 b. Likewise, a lower region 38 a, 38 b of the upper backrest side elements 7 a, 7 b has substantially the shape of an irregular right-angled triangle. The hypotenuse of this triangle forms the lower edge of the upper backrest side elements 7 a, 7 b facing the slot. In the initial position, a distance 40 a, 40 b between the upper 7 a, 7 b and the lower backrest side elements 6 a, 6 b or the slot width is constant along the entire length of the slot 11 a, 11 b.

In the outer regions 13 a, 13 b of the left side portion 9 a and of the right side portion 9 b of the backrest part 3, a joint device 8 a, 8 b is provided, which is arranged at least in portions in the associated slot 11 a, 11 b.

The respective joint device 8 a, 8 b comprises a swivel joint 16 and a ball joint 17. Furthermore, the swivel joint 16 is rotatably arranged on the lower backrest side element 6 a, 6 b. A connecting rod element 18 connects the swivel joint 16 and a ball joint 17, wherein a ball socket 19 of the ball joint 17 in which a ball head 20 of the ball joint 17 is received is arranged on the connecting rod element 18. The ball head 20 is connected to the upper backrest side element 7 a, 7 b or a lower edge of the upper backrest side element 7 a, 7 b by means of a ball stud 21. The swivel joint 16 is pivotably attached to the plate-like element forming the lower backrest side element 6 a, 6 b. The upper edge of the lower backrest side element 6 a, 6 b protrudes forwards, as already described, whereby an upholstery element 29 can be accommodated. In this edge an elongated recess is provided which runs along the longitudinal extent of the slot 11 a, 11 b and is oriented towards the slot. The connecting rod element 18 protrudes through the recess. The ball joint 17 is arranged in the slot 11 a, 11 b. When pivoted about the axis of rotation of the swivel joint 16, the connecting rod element moves in the recess of the upper edge along the longitudinal extent of the slot 11 a, 11 b.

When the middle backrest element 5 is pivoted, the distance 40 a, 40 b between a lower backrest side element 6 a, 6 b and an upper backrest side element 7 a, 7 b changes at least in the inner region 12 a, 12 b of a side portion 9 a, 9 b of the backrest part 3 due to the mechanical couplings and a deflection of the joint device 8 a, 8 b.

A turning movement of an occupant causes a force to be introduced into the backrest part 2. Depending on the seated posture of the occupant, this introduction of force acts on one, several or all of the at least five backrest elements 5, 6 a, 6 b, 7 a, 7 b. Due to the mechanical couplings of the upper backrest side elements 7 a, 7 b and lower backrest side elements 6 a, 6 b to the middle backrest element 5, the introduction of force is transmitted to all backrest elements 5, 6 a, 6 b, 7 a, 7 b. The introduction of force caused by the rotary movement causes pivoting of the middle backrest element 5 and pivoting of the two lower backrest side elements 6 a, 6 b relative to the backrest base element 4. The middle backrest element 5 is pivoted in directions parallel to the width axis Y. If the occupant turns to the right in order to look over his right shoulder, the middle backrest element 5 is pivoted to the left. A corresponding introduction of force can take place, for example, via a pushing movement of the occupant's shoulder on a side portion 9 a, 9 b. Pivoting of the middle backrest element 5 causes pivoting of the lower backrest side elements 6 a, 6 b about the pivot axes SA2, SA3 due to the forced control of the first coupling mechanism 15. Furthermore, the pivoting of the middle backrest element 5 causes a translation of the upper backrest side elements 7 a, 7 b along the longitudinal axis LA of the middle backrest element 5 and at the same time a rotation of the upper backrest side elements 7 a, 7 b about the axes of rotation DA. As a result of these movements and a corresponding deflection of the joint device 8 a, 8 b, an upper edge region 30 a, 30 b of the lower backrest side element 6 a, 6 b and a lower edge region 31 a, 31 b of the upper backrest side element 7 a, 7 b move out of the second plane E2 and the third plane E3, respectively. An upper edge region 30 a, 30 b of the lower backrest side element 6 a, 6 b and a lower edge region 31 a, 31 b of the upper backrest side element 7 a, 7 b move out of the associated plane in the direction towards the occupant when the pivoting in the direction of this backrest side element 6 a, 6 b, 7 a, 7 b takes place. An upper edge region 30 a, 30 b of the lower backrest side element 6 a, 6 b and a lower edge region 31 a, 31 b of the upper backrest side element 7 a, 7 b move out of the associated plane in the direction towards the occupant when the pivoting in the opposite direction to this backrest side element 6 a, 6 b, 7 a, 7 b takes place. When the middle backrest element 5 is pivoted towards a side portion 9 a, 9 b of the backrest part 3, the angle α_(L), α_(R) is thus an obtuse angle, i.e. an angle greater than 90° and less than 180°, the angles α_(L), α_(R) is substantially 180° in the initial position. When the middle backrest element 5 is pivoted away from a side portion 9 a, 9 b of the backrest part 3, the angle α_(L), α_(R) is thus a reflex angle, i.e. an angle greater than 180°. The angles α_(L), α_(R) are advantageously enclosed by the surfaces of the backrest side elements 6 a, 6 b, 7 a, 7 b or the plate-like elements of the backrest side elements 6 a, 6 b, 7 a, 7 b.

Due to the protrusion of the backrest side elements 6 a, 6 b, 7 a, 7 b, a kind of bulged bearing/support surface is created for the occupant, which is formed by the upholstery elements 29 or the backrest side elements 6 a, 6 b, 7 a, 7 b themselves. In the case of pivoting to the left, for example, the angle α_(L) is formed as an obtuse angle, and the angle α_(R) is formed as a reflex angle. Thus, the left upper and lower backrest side elements 6 a, 7 a protrude and form a kind of bulge. Such a bulge supports the bent posture of the upper body in a seated turning position. The vehicle seat 1 thus offers an ergonomically optimal adaptation of the backrest part 3 to a turning movement of an occupant. Furthermore, such pivoting or rotation of the backrest part can also serve to isolate transverse accelerations (swaying).

The described movements of the upper and lower backrest side elements 6 a, 6 b, 7 a, 7 b result in a deflection of the ball joints 17 of the joint devices 8 a, 8 b along several degrees of freedom, in particular a rotation of the ball head about the axis of the ball stud and a rotation of the ball head 16 in the ball socket 19, and also a rotation of the connecting rod element 18 about an axis of rotation of the swivel joint 16 of the joint device 8 a, 8 b. When pivoted in the direction of a side portion 9 a, 9 b of the backrest part 3, the connecting rod is rotated in such a way that the ball joint 17 moves in the direction of the middle backrest element 5. In the case of the opposite joint element 8 a, 8 b, this rotation is correspondingly reversed. When the middle backrest element 5 is pivoted, the distance 40 a, 40 b between a lower backrest side element 6 a, 6 b and an upper backrest side element 7 a, 7 b, or the slot width at least in the inner region 12 a, 12 b of a side portion 9 a, 9 b of the backrest part 3, changes due to the mechanical couplings and a deflection of the joint device 8 a, 8 b. In FIG. 7b, 7c, 13b, 13c , for example, it can be clearly seen that the upper edge of the lower backrest side elements 6 a, 6 b facing the slot 11 a, 11 b and the lower edge of the upper backrest side elements 7 a, 7 b facing the slot in the inner region 12 a, 12 b of a side portion bear against one another in portions. These regions are marked with a circle 48 in each of these drawings.

According to a further embodiment, the middle backrest element 5 is designed in two parts. The middle backrest element 5 accordingly comprises an upper portion 5 a and a lower portion 5 b. The two portions 5 a, 5 b of the middle backrest element 5 are connected to one another by a further joint device 44. The further joint device 44 or the division of the middle backrest element 5 is arranged in a lower region of the middle backrest element 5. The further joint device 44 is advantageously arranged in or above the lumbar region of the occupant. Thus, by pivoting of the upper portion 5 a relative to the lower portion 5 b, a posture adjustment or a lordosis/kyphosis of the occupant can be compensated for. Advantageously, the inclination of the upper portion 5 a of the middle backrest element 5 can be adjusted hydraulically, pneumatically or manually by an actuating drive, for example an electric motor.

According to a further embodiment, a locking device 33 is provided, by means of which a rotational position 10 a, 10 b, 10 c of the backrest part 3 can be locked. Furthermore, it would be conceivable that a resetting device is provided, which returns the backrest part 3 to its initial position 10 c. On the first fastening element 23, a pin 46 is provided which extends along the longitudinal axis X into the backrest base element 4. A pair of springs 47 a, 47 b is provided within the backrest base element 4. The pin 46 is arranged between the springs 47 a, 47 b of the pair of springs and is operatively connected to them or is fastened to one end of each spring 47 a, 47 b. The other end of the springs is connected to the backrest base element 4. This can be seen clearly in FIG. 10e . By pivoting of the first fastening element 23, the pin 46 is displaced along the width axis Y. One of the springs 47 a, 47 b is thus compressed and a further spring 47 a, 47 b is expanded. The corresponding spring forces can bring about a return of the backrest part 3 to the initial position 10 c. The displacement of the pin 46 can be locked by the locking device 33, whereby the pivoting of the first fastening element 23 can be locked. The pivoting of the entire backrest part 3 can be locked by the mechanical couplings.

According to a further embodiment, a drive unit 34 is provided, by means of which the backrest part 3 can be brought into a rotational position 10 a, 10 b, 10 c. The drive unit 34 could, for example, drive the displacement of the pin 46 along the width axis Y and thus the pivoting of the first fastening element 23 or the entire backrest part 3. The drive unit 34 can be, for example, an electric actuating drive, a pneumatic, hydraulic or some other drive.

The applicant reserves the right to claim all the features disclosed in the application documents as essential to the invention, provided that these are novel, individually or in combination, over the prior art. It is further pointed out that features which in themselves can be advantageous have also been described in the individual drawings. A person skilled in the art will immediately recognize that a particular feature described in one drawing can also be advantageous without adopting further features from this drawing. Furthermore, a person skilled in the art will recognize that advantages can also result from a combination of a plurality of features shown in individual or in different drawings.

LIST OF REFERENCE SIGNS

1 vehicle seat

2 backrest

3 backrest part

4 backrest base element

4 a left side region of the backrest base element

4 b right side region of the backrest base element

4 c middle region of the backrest base element

5 middle backrest element

5 a upper portion of the middle backrest element

5 b lower portion of the middle element

6 a left lower backrest side element

6 b right lower backrest side element

7 a left upper backrest side element

7 b right upper backrest side element

8 a joint device

8 b joint device

9 a left side portion

9 b right side portion

10 a second rotational position of the backrest

10 b third rotational position of the backrest

10 c first rotational position (initial position) of the backrest

11 a slot

11 b slot

12 a inner region of the left side portion

12 b inner region of the right side portion

13 a outer region of the left side portion

13 b outer region of the right side portion

14 first coupling mechanism

15 second coupling mechanism

16 swivel joint

17 ball joint

18 connecting rod element

19 ball socket

20 ball head

21 ball stud

22 a guide device on the left

22 b guide device on the right

23 first fastening element

24 second fastening element

25 third fastening element

26 first coupling rod

27 second coupling rod

28 ball joint

29 upholstery elements

30 a upper edge region of the lower backrest side element

30 b upper edge region of the lower backrest side element

31 a lower edge region of the upper backrest side element

31 b lower edge region of the upper backrest side element

32 seat base element

33 locking device

34 drive device

35 seat part

36 support elements

37 a, 37 b upper region of the lower backrest side elements

38 a, 38 b lower region of the upper backrest side elements

39 horizontal axis

40 a, 40 b distance

41 sliding rod

42 holding elements

43 sliding element

44 further joint device

45 resetting device

46 pin

47 a, 47 b springs

48 region

A1 first axis

A2 second axis

DA axis of rotation

E1 first plane

E2 second side plane

E3 third side plane

LA longitudinal axis of the middle backrest element

SA1 first pivot axis

SA2 second pivot axis

SA3 third pivot axis

NA axis of inclination

α_(L) angle on the left

α_(R) angle on the right

β₁ first angle of inclination

β₂ second angle of inclination

γ₂ angle between pivot axis SA2 and plane

γ₃ angle between pivot axis SA3 and plane

δ angle of the slot with the horizontal axis

X depth axis

Y width axis

Z height axis 

What is claimed is:
 1. A vehicle seat having a backrest, which comprises a backrest part and a backrest base element, the backrest part comprising a middle backrest element which is arranged pivotably on the backrest base element, wherein the backrest part comprises two lower backrest side elements and two upper backrest side elements, which are each mechanically coupled to the middle backrest element, wherein the two lower backrest side elements are arranged pivotably on the backrest base element, wherein at least one joint device is provided in each case between a lower backrest side element and an upper backrest side element, wherein a lower backrest side element and an upper backrest side element are arranged at an angle to one another, wherein pivoting of the middle backrest element causes a change in the angle.
 2. The vehicle seat according to claim 1, wherein a lower backrest side element and an upper backrest side element are arranged on the left side of the middle backrest element and form a left side portion of the backrest part, wherein a lower backrest side element and an upper backrest side element are arranged on the right side of the middle backrest element and form a right side portion of the backrest part, wherein in a initial position of the backrest the middle backrest element is arranged substantially in a first plane which is spanned by a height axis of the backrest and a width axis of the backrest, wherein in the basic position of the backrest the left side portion of the backrest part is arranged substantially in a second side plane which is spanned by the height axis of the backrest and a first axis, wherein in the initial position of the backrest the right side portion of the backrest part is arranged substantially in a third side plane which is defined by the height axis of the backrest and a second axis, wherein the width axis and the first axis enclose a first angle of inclination, wherein the width axis and second axis enclose an angle of inclination.
 3. The vehicle seat according to claim 1, wherein at least in the initial position of the backrest, the upper backrest side elements and the lower backrest side elements are spaced apart from one another, wherein at least in the initial position of the backrest a slot is formed between the upper backrest side elements and the lower backrest side elements, wherein the slot extends from an inner region of a side portion of the backrest part obliquely upwards along the height axis to an outer region of a side portion of the backrest part.
 4. The vehicle seat according to claim 1, wherein a first coupling mechanism is provided, by means of which the middle backrest element is mechanically coupled to the two lower backrest side elements, wherein a second coupling mechanism is provided, by means of which the middle backrest element is mechanically coupled to the two upper backrest side elements, wherein a force is introduced into the backrest part by a turning movement of an occupant, wherein the introduction of force causes the middle backrest element and the two lower backrest side elements to pivot relative to the backrest base element.
 5. The vehicle seat according to claim 4, wherein a joint device is provided in each of the outer regions of the left side portion and of the right side portion of the backrest part, wherein the at least one joint device is arranged at least in portions in the associated slot, wherein when the middle backrest element is pivoted, the distance between a lower backrest side element and an upper backrest side element changes at least in the inner region of a side portion of the backrest part due to the mechanical couplings and a deflection of the joint device.
 6. The vehicle seat according to claim 1, wherein the respective joint device comprises a swivel joint and a ball joint, wherein a connecting rod element is rotatably arranged on the lower backrest side element through the swivel joint, wherein a ball socket of the ball joint, in which a ball head of the ball joint is received, is arranged on the connecting rod element, wherein the ball head is connected by means of a ball stud to the upper backrest side element.
 7. The vehicle seat according to claim 1, wherein the second coupling mechanism comprises a guide device, by means of which in each case an upper backrest side element is arranged on the middle backrest element, wherein the guide device allows a translational movement of the upper backrest side element relative to the middle backrest element along a longitudinal axis of the middle backrest element, wherein the guide device allows a rotary movement of the upper backrest side element relative to the middle backrest element about an axis of rotation which runs parallel to the longitudinal axis of the middle backrest element.
 8. The vehicle seat according to claim 2, wherein the backrest base element has a middle region which extends substantially parallel to the first plane, wherein the backrest base element has two side regions, wherein a left side region of the backrest base element extends substantially parallel to the second side plane, wherein a right side region of the backrest base element extends substantially parallel to the third side plane.
 9. The vehicle seat according to claim 8, wherein the lower backrest side elements are in each case arranged on the side regions of the backrest base element so as to be pivotable about a second pivot axis or a third pivot axis, wherein the second pivot axis and the third pivot axis extend obliquely upwards along the longitudinal axis and the height axis, wherein a second fastening element is provided, which is firmly connected to the lower backrest side element arranged on the left and which is pivotable about the second pivot axis, wherein a third fastening device is provided, which is firmly connected to the lower backrest side element arranged on the right side and which is pivotable about the third pivot axis.
 10. The vehicle seat according to claim 4, wherein the first coupling mechanism transmits a pivoting movement of a first fastening element to the second fastening element and the third fastening element and vice versa, wherein the first coupling mechanism has a first coupling rod which connects the first fastening element and the second fastening element, wherein the first coupling mechanism has a second coupling rod which connects the first fastening element and the third fastening element.
 11. The vehicle seat according to claim 1, wherein the upper backrest side elements and the lower backrest side elements are designed as plate-like elements, wherein the plate-like elements are designed to accommodate upholstery elements.
 12. The vehicle seat according to claim 1, wherein when the middle backrest element is pivoted towards a side portion of the backrest part the angle is an obtuse angle, wherein when the middle backrest element is pivoted towards a side portion of the backrest part an upper edge region of a lower backrest side element and a lower edge region of the upper backrest side element are displaced forwards at least in an outer edge region of the side portion along the longitudinal axis.
 13. The vehicle seat according to claim 1, wherein the middle backrest element is designed in two parts, wherein the two portions of the middle backrest element are connected to one another by a further joint device, wherein the joint device is arranged in a lower region of the middle backrest element, wherein an upper portion of the middle backrest element is pivotable relative to the lower portion along the longitudinal axis.
 14. The vehicle seat according to claim 1, wherein a locking device is provided, by means of which a rotational position of the backrest part can be locked, wherein a resetting device is provided, by means of which the backrest part can be returned to the initial position.
 15. The vehicle seat according to claim 1, wherein a drive unit is provided, by means of which the backrest part can be brought into a rotational position. 